


Symbiotic Relationship

by MyGhostJustYells



Category: Yu-Gi-Oh! Duel Monsters (Anime & Manga)
Genre: Antagonistic Brotherly Bonding, Dimension Travel, Family Drama, Fix-It of Sorts, Gen, Kaiba Seto Has Issues, Manga and Anime Crossover, Noah Kaiba Has Issues, YGOME2020, Yami Yuugi/Atem (Mentioned)
Language: English
Status: Completed
Published: 2020-11-18
Updated: 2020-11-18
Packaged: 2021-03-09 23:48:56
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,761
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27614416
Author URL: https://archiveofourown.org/users/MyGhostJustYells/pseuds/MyGhostJustYells
Summary: When Seto crashes his craft into a new dimension while attempting to return home, he meets another Kaiba he never knew existed.
Comments: 5
Kudos: 12
Collections: Yu-Gi-Oh! It's Time to G-G-G-Gift! [Mini-Exchange]





	Symbiotic Relationship

**Author's Note:**

  * For [rainstormcolors](https://archiveofourown.org/users/rainstormcolors/gifts).



> Title: Symbiotic Relationship  
> Author: MyGhostJustYells  
> Fandom: Yu-Gi-Oh!: Duel Monsters  
> Rating: T  
> Warning(s): None.  
> Disclaimer: I do not own Yu-Gi-Oh! or its characters. They belong to Kazuki Takahashi, Studio Gallop, TV Tokyo, and other licensors and distributors. This is a not-for-profit fan work.
> 
> Author's Note: Written for the 2020 Yu-Gi-Oh! It's Time to G-G-G-Gift! [Mini-Exchange] for rainstormcolors. This was an interesting prompt that I had to dig into a lot of details for. I hope you like it!

The craft slammed into the ground with truly alarming speed. Seto Kaiba had to consciously unclench his jaw as he took a deep breath to calm his racing heart. He glanced down and noted absently that his hands were shaking.

Taking a brief moment to pull himself together, his deep blue eyes glanced up, noting their surroundings. His dimension craft had crashed in the middle of a field, a brilliant green field sprinkled with white wildflowers. In the distance, the KaibaCorp tower was especially prominent against the Domino skyline.

Well, it had been the beginnings of spring when he left, so this seemed right. He must have made it back home.

Sighing deeply and with a hint of intense frustration, he reached for the release and the latch clicked open. As soon as the hatch opened, though, his brows furrowed and his eyes narrowed. Something wasn’t right, even though he couldn’t quite put his finger on it.

As the last visages of his disorientation evaporated, where he was became clear. He should have recognized the unmistakable signs of his surroundings being virtual immediately. But how on Earth…?

Before that line of thought could go any farther, a pillar of light which quickly materialized into a small boy suddenly appeared to the side of the craft. But what really surprised Seto was that the boy looked exactly like…

The boy glared at him with scorn and what appeared to be a dejected tiredness. His voice reflected those feelings perfectly. “Have you come back to gloat?”

Seto’s confusion was growing by the second. “I don’t know who you think I am, but I have never seen you before in my life.”

Now it was the boy’s turn to narrow his eyes in confusion, as well as irritation. “You’re playing dumb with me? Seriously?”

Seto’s response to that was a short burst of laughter. “I can assure you that ‘playing dumb’ is something I have never even considered doing.”

“Stop insulting me.”

Now Seto was getting annoyed. “I’ll say it again. I have no idea who you are. Who are you? And why… do you look exactly like me?”

Frustrated, the boy snapped, “It’s me. Noah. You know, the one who kidnapped you and the contestants in your precious tournament into my virtual world.” A pause. “You really don’t remember.”

“That’s what I’ve been trying to tell you, yes.”

“But… how is that possible? Did you hit your head harder in that crash than it looked?”

“No, I am perfectly fine.”

“And how or why did you even get here?” Noah glanced down at the craft, almost suspiciously.

The wheels in Seto’s brain turned, finally arriving at the most plausible conclusion. “I must have ended up in a different dimension,” he groaned, rubbing his forehead.

“Come again?”

“This is a dimensional travel craft that I invented. It lets me travel between different dimensions.”

“I gathered that, genius,” Noah said sarcastically. “So, we’re dealing with multiverse theory here.” It wasn’t a question, more of a musing statement.

“Most likely.” It would certainly explain much of what was happening here.

An uncomfortable silence passed as Seto climbed out of the dimension craft with a catlike grace.

Noah regarded him with a thoroughly unwelcoming expression. “So… when are you going to leave?”

Seto glared at him. “The craft is obviously damaged, and even if it wasn’t, it’s going to need time to recharge before it can make another jump.”

Noah suddenly started to look a little nervous. “Well, I don’t care where you came from – you shouldn’t stay around here. It isn’t safe.”

“Surprisingly, I won’t be able to leave until my craft is fixed.” Sarcasm dripped from his words. “You have access to this virtual world, don’t you?”

“Of course I do. I’ve been living in it for six years.”

That comment surprised Seto, but he did his best not to let it show. “Then you should be able to manipulate the surrounding data to repair my craft pretty easily.”

Noah’s eyes narrowed. “Why would you expect me to help you? If you’re not the Seto I know, then I’ve never even met you before in my life.”

“Because I need to get back and try again. And I need to get back to my brother.” His words were short, clipped.

Noah’s expression suddenly… changed. “Mokuba?”

Seto glanced away, as if feeling he had revealed too much. “Yes.”

Noah looked towards the sky, his eyes narrowing at something Seto couldn’t see or understand. “We can’t stay here. He’ll find us. I’ll help you, but you need to come with me.”

Seto shook his head sharply. “Not until you tell me who ‘he’ is.”

The pain in Noah’s eyes was all too raw. “My father. Gozaburo Kaiba.”

Seto’s eyes widened. “What?” His voice pulsed with venom.

“I’m his biological son.” Noah said it softly.

“Then how have I never heard of you before?”

“Look, if you haven’t heard of me by now, I either don’t exist in your world or… I died there too and Father either didn’t try or was unable to save me. Now, come with me. I’ll help you repair your craft, but we can’t be found by Father. He… isn’t very human anymore.”

An uneasy feeling settled in Seto’s stomach at the boy’s words and the tone in which he conveyed them. “What about the craft?”

“Leave it. It’s not what he’s after.”

With a tight expression that had a shade of concern to it, Seto moved to follow Noah.

They left the field and the disconcerting feeling behind, heading into a forest instead of the city. A narrow path wound through the picture-perfect trees.

It was Seto who broke the silence. “What… happened between us?”

After a brief moment of hesitation, Noah told him. He related the time he had pulled all of them into the virtual world, as well as his own past and what he knew about his world’s Seto.

“I suppose I just have one question,” said Seto as Noah finished. “If you blew up this virtual world with a missile, why is it, as well as you and Gozaburo, still here?”

Noah looked tired. “My best guess is that the explosion didn’t destroy the systems supporting the virtual world entirely. The mobile fortress must have protected them better than I had anticipated. Still, it doesn’t matter. This place… me… we’re living on borrowed time.” A pause. “Even if it didn’t destroy this world completely, the explosion still damaged it. It’s degrading.”

Seto guessed that to be true from the telltale signs of the environment around them breaking down, data flaking away before disappearing if one looked close enough.

“Why haven’t you reached out for help?”

Noah released a deep breath. “Two reasons. One, I deleted all the exits right before the missile was going to strike, shutting this virtual world off from all other networks. So I really have no way out. As for the second…” He looked away. “I’m already dead. Soon, I’ll be dead for real. And besides… I deserve it for all I did.”

Seto’s response was silence, though his jaw was suddenly rather set, as if Noah’s words had angered him.

“And what about you?” Noah said, pointedly turning the focus off of himself. “Why on Earth are you flying around between different dimensions in that deathtrap?”

Now Seto’s anger was not just implied, though for a long time he answered Noah’s inquiry with silence. It had about gotten to the point where Noah began to assume he wouldn’t be getting an answer at all. _Typical._

But then Seto did speak, his words not what Noah had expected.

“I lost. Again.”

He sounded so angry about this. So broken. Now that Noah observed him more closely, this Seto seemed unwell. Tired, in pain both physical and emotional, haunted. He was excellent at hiding it but seemed very near the end of his rope.

Noah supposed he looked similar, only resigned instead of angry.

“Lost to whom?”

Seto released a breath through his nose. “The Pharaoh.”

It took Noah a moment to even hazard a guess as to what he was talking about. “The Pharaoh? You mean that presence inside of Yuugi Mutou?” He had indeed felt that presence when he’d tried to take Yuugi’s body for himself. Seen that other being’s true form. He had sure looked like a Pharaoh, and was about the only person Noah thought Seto could be referring to, given his known obsession with defeating Yuugi. Though perhaps it had been the moniker of some other Duelist who had surpassed him, or even someone who didn’t exist in Noah’s dimension at all.

“It doesn’t surprise me that you would have crossed paths with him,” Seto said softly. “For the longest time I just thought my classmate Yuugi Mutou had Dissociative Identity Disorder or something, but it…” He paused, clearly questioning how much he wanted to give away.

“Look, we’re never going to see each other again once you leave here,” Noah said. “I told you my story, are you not going to tell me yours?”

Seto glanced at him but, never one to back down from a challenge, continued. “It eventually became apparent that Yuugi’s ‘other personality’ was really an ancient Egyptian ghost dwelling within the Millennium Puzzle.”

Noah raised an eyebrow. “Seriously?”

“Unfortunately.”

“Okaaay, so you still haven’t told me why this ancient ghost possessing some jewelry caused you to invent interdimensional travel.”

It took Seto a long time to answer, as if he wasn’t even sure what the answer was. Then he said, “He left before we could settle our score. He Dueled Yuugi in some Ceremonial Duel with the condition that if he lost, he’d get to move on to the afterlife. And Yuugi won. The Pharaoh _left me_ before we could have our rematch.”

Noah squinted, trying to puzzle this all out. “So you… invented interdimensional travel, to go play a game of Duel Monsters in the afterlife, against some dead guy?”

Seto’s silence told him everything he needed to know.

“Did you win?”

“What do you think?”

“And I think you mentioned earlier that you are going to go _back_ and try again?”

Seto made a noncommittal noise.

“I think you have some abandonment issues.”

Seto turned his icy glare on Noah. “Shut up. You have no idea what I’ve been through in my life.”

But Noah returned the look without flinching. “If you think being abandoned, being left alone again, isn’t the thing that scares me most, then you’re wrong.”

Seto continued to glare but didn’t say anything, his mouth set in a tight line. “My craft should be finished recharging now.”

Noah nodded. “Then let’s get back and I’ll do what I can to repair it.”

The two Kaiba brothers who had never known each other started back towards the crash site, taking a different path that was much narrower and better concealed. That oppressive feeling was back in the air again, much like when Gozaburo had walked in on Seto’s lessons when he was a child. The sensation was much stronger now.

They were just about to leave the thick cover of the forest for a more wide-open field on the outskirts of the city when Noah reached out an arm to stop Seto from moving forward. The boy’s expression had turned fearful. “Wait.”

Seto did, the oppressive aura nigh suffocating.

From behind a row of trees shambled a large, red… monster. That was the best word Seto Kaiba could find to describe it. He couldn’t tell if it was oozing some noxious substance or on fire, and he wasn’t keen on getting close enough to find out.

“T-that’s Gozaburo?” Seto whispered, despising how strained, how fearful, his voice sounded to his own ears.

“Yeah,” said Noah. “Don’t speak and don’t move. We’ll be fine so long as he doesn’t notice us.”

The monster that had once been Gozaburo Kaiba shambled along the treeline, trees cracking as they split in two under its steps. In its incoherent moaning and occasional roars, Seto swore he could hear the words “Seto” and “Noah.” A shiver ran unbidden down his spine.

After what felt like an eternity had passed, the monster vanished out of sight into the city, smashing a building as it went. It apparently hadn’t noticed them.

Seto exhaled a breath he hadn’t realized he’d been holding and said to Noah, “How long have you been living like this?”

Noah’s expression darkened. “Too long. At least you don’t have to share my fate, and at least I won’t have to be like this for much longer.”

The silence that hung around them during their walk back to the dimension craft felt heavy, as if nothing could lift it. Soon, they arrived back at the crash site, the sense of urgency palpable.

“Alright. Stand back and let me see what I can do,” Noah said. He focused intensely on the craft, brow furrowed in concentration. Within seconds, glowing light began to envelop the damaged edges of the craft, and it began to mend together again.

“Can I offer you some advice?” Noah said after working in silence for several moments.

“I get the feeling you’re going to give it anyway.”

“I know what my father taught you. Because he taught me the same thing. Being the best is everything, and losers deserve nothing. I know this is why you’re so fixated on this Pharaoh.”

Seto said nothing and didn’t look at him, only staring ahead with a hard expression.

“But I don’t even understand that. If Yuugi and the Pharaoh faced off to determine if he would go on to the afterlife or stay behind, then the Pharaoh _lost_. He’s only second best. Why hasn’t your brain switched over to seeing _Yuugi_ as your rival?”

Seto blinked slowly, processing the logic as the glow vanished from the serrated edges of the craft’s metal, now entirely whole again.

Noah continued, much softer. “You’ve already lost to Yuugi, what, three times now?”

“Four,” Seto corrected absentmindedly. “Wait, have you been stalking my counterpart?”

“I did my research,” Noah said with a sniff. “And extrapolated the rest.”

Seto felt a strange sense of irritation rise up within him. _Damn. The me in this dimension has lost to Yuugi_ fewer times.

Noah continued. “So if those first four times didn’t help you move past all the crap my father filled your head with, what makes you think a fifth, sixth, seventh will be any different?”

“Why should I care what you think?” Seto snapped. “A loser who doesn’t even have the courage to keep fighting, who has just given up!”

“Didn’t you do the same?” Noah bit back harshly. “I can’t imagine _a trip to the afterlife_ carried no risk to your life.” Then his eyes narrowed in anger as he pieced together what this meant. “And Mokuba,” he said, aghast. “You could have died and left your brother all alone! Good God, Seto, Mokuba needs you – you’re all he has! How could you even consider leaving him?!”

“And what about you? How could you just give up and refuse to keep fighting?” Seto snapped. “You don’t want to die. Even I can see that.”

Noah’s eyes widened in shock, then narrowed in anger. “At this point, what choice do I have? I’m trapped here, in this dying world, with no way to even send a message to the outside, let alone escape!”

A massive rumble suddenly shook the ground, like a giant footfall, putting an instant halt to the barbed words being exchanged. The Gozaburo monster came into view from behind a skyscraper, looking straight in their direction with its hollow eyes.

“Uh oh. I think he’s sensing the manipulations in the system,” Noah said nervously. “You need to go, now. The craft is fixed.” There was a pause before, voice thick with emotion, he said, “Go back to Mokuba and never, ever take him for granted.”

After a beat, Seto climbed inside, clicking on the safety belts and connecting all the necessary wires. “Here,” he said, handing Noah a small data drive while he booted up the craft’s systems with his other hand. “These are the basic instructions for systems built around Solid Vision, which should include escape directions for scenarios where exit point data has been damaged or deleted. Do with it what you will.”

Noah took the small drive, looking at it with something that might have been disbelief, tinted with hope.

Seto inclined his head. “Good luck.”

Noah did the same. “You too.”


End file.
